Preparation and structure of new phenylplatinum complexes containing silsesquioxane as a monodentate or bidentate ligand

Article abstract of DOI:10.1021/om060192s

Incompletely condensed silsesquioxanes, R₇Si₇D ₉(OH)₃ (R = cyclo-C₅H₉, iso-C ₄H₉), react with trans-[PtI(Ph)(L)₂] (L = PEt₃, PMe₂Ph) at room temperature in the presence of Ag₂O to yield platinum complexes with a monodentate O-coordinated silsesquioxane, trans-[Pt{O₁₀Si₇R₇(OH) ₂}(Ph)(L)₂] (1a: R = cyclo-C₅H₉; L = PEt₃, 1b: R = iso-C₄H₉; L = PEt₃, 2a: R = cyclo-C₅H₉; L = PMe₂Ph, 2b: R = iso-C₄H₉; L = PMe₂Ph). Reactions of silsesquioxanes with trans-[PtI(Ph)(PPh₃)₂] in the presence of Ag₂O at 55°C afford unexpected Pt-Ag heterobimetallic complexes, [Pt{O₁₁Si₇R ₇(OH)(AgPPh₃)}(Ph)(PPh₃)] (3a: R = cyclo-C ₅H₉, 3b: R = iso-C₄H₉), and a hydroxo-bridged dinuclear platinum complex, anti-[{PtPh-(PPh₃)} ₂(μ-OH)₂] (4). These complexes were isolated and characterized by X-ray crystallography and ¹H, ³¹P, ²⁹Si, and ¹³C NMR spectroscopy. The crystal structures of 3a and 3b show a square-planar coordination around the Pt center bonded to Ph, PPh₃, and bidentate O,O-coordinated silsesquioxane. One of the coordinated oxygen atoms is also bound to the AgPPh₃ group.

Full text of DOI:10.1021/om060192s

3776
Organometallics 2006, 25, 3776-3783
Preparation and Structure of New Phenylplatinum Complexes
Containing Silsesquioxane as a Monodentate or Bidentate Ligand
Neli Mintcheva, Makoto Tanabe, and Kohtaro Osakada*
Chemical Resources Laboratory (Mail Box R1-3), Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama 226-8503, Japan
ReceiVed February 28, 2006
Incompletely condensed silsesquioxanes, R7Si7O9(OH)3 (R ) cyclo-C5H9, iso-C4H9), react with trans-
[PtI(Ph)(L)2] (L ) PEt3, PMe2Ph) at room temperature in the presence of Ag2O to yield platinum complexes
with a monodentate O-coordinated silsesquioxane, trans-[Pt{O10Si7R7(OH)2}(Ph)(L)2] (1a: R ) cyclo-
C5H9; L ) PEt3, 1b: R ) iso-C4H9; L ) PEt3, 2a: R ) cyclo-C5H9; L ) PMe2Ph, 2b: R ) iso-C4H9;
L ) PMe2Ph). Reactions of silsesquioxanes with trans-[PtI(Ph)(PPh3)2] in the presence of Ag2O at 55
°C afford unexpected Pt-Ag heterobimetallic complexes, [Pt{O11Si7R7(OH)(AgPPh3)}(Ph)(PPh3)] (3a:
R ) cyclo-C5H9, 3b: R ) iso-C4H9), and a hydroxo-bridged dinuclear platinum complex, anti-[{PtPh-
(PPh3)}2(µ-OH)2] (4). These complexes were isolated and characterized by X-ray crystallography and
1H, 31P, 29Si, and 13C NMR spectroscopy. The crystal structures of 3a and 3b show a square-planar
coordination around the Pt center bonded to Ph, PPh3, and bidentate O,O-coordinated silsesquioxane.
One of the coordinated oxygen atoms is also bound to the AgPPh3 group.
as O,O-chelating bidentate ligands. Pt complexes with Pt-O-
Si bonds were obtained using simple silanolate as ligand.
Komiya reported a metathesis reaction of sodium silanolate with
an alkylplatinum halogeno complex to afford PtEt(OSiPh3)-
(cod).8 Recently, we have employed Ag2O to activate both the
OH bond of silanol and the Pt-I bond of trans-[PtI(Ph)(PPh3)2]
and obtained trans-[Pt{OSiMe2(C6H4CF3-4)}(Ph)(PPh3)2] as the
product of the metathesis reaction.9 An analogous reaction of
silanol, HOSiMe2(C6H4CF3-4) with [PtBr(PEt3)3]+, however
forms diarylplatinum complexes via the initial formation of an
intermediate silanolato platinum complex and its C-Si bond
cleavage.10 The introduction of a bulky and partially hydrophilic
silsesquioxane ligand to aryl(or alkyl)platinum complexes would
provide complexes with unique chemical properties. In this
paper, we report the preparation and structure of new platinum-
containing silsesquioxanes with monodentate ligands and un-
expected Pt-Ag heterobimetallic silsesquioxanes with bidentate
ligands.
Introduction
Incompletely condensed silsesquioxanes1 contain a network
composed of Si-O bonds and OH groups and are regarded as
partial structures of the silica surface used for heterogeneous
catalysts.2 Silsesquioxane complexes of transition metals cata-
lyze the polymerization and epoxidation of alkenes.2d Inspite
of the many reports on early-transition metal complexes with
silsesquioxane ligands3,4 and late-transition metal complexes
with silsesquioxane-based phosphine ligands,5 there have been
a few reports on group 10 metal complexes having O-bonded
silsesquioxanes as ligand. Recently, Abbenhuis6 and Johnson7
have reported platinum complexes that contain silsesquioxanes
* To whom correspondence should be addressed. E-mail: kosakada@
res.titech.ac.jp.
(1) (a) Feher, F. J.; Budzichowski, T. A.; Blanski, R. L.; Weller, K. J.;
Ziller, J. W. Organometallics 1991, 10, 2526-2528. (b) Feher, F. J.;
Terroba, R.; Ziller, J. W. Chem. Commun. 1999, 2309-2310. (c) Feher, F.
J.; Newman, D. A.; Walzer, J. F. J. Am. Chem. Soc. 1989, 111, 1741-
1748. (d) Feher, F. J.; Newman, D. A. J. Am. Chem. Soc. 1990, 112, 1931-
1936.
(2) For reviews, see: (a) Feher, F. J.; Budzichowski, T. A. Polyhedron
1995, 14, 3239-3253. (b) Murugavel, R.; Voigt, A.; Walawalkar, M. G.;
Roesky, H. W. Chem. ReV. 1996, 96, 2205-2236. (c) Mitsudo, T.; Wada,
K. Shokubai 2000, 42, 282; Chem. Abstr. 2000, 133, 95041r. (d) Abbenhuis,
H. C. L. Chem. Eur. J. 2000, 6, 25-32. (e) Lorenz, V.; Fischer, A.;
Giessmann, S.; Gilje, J. W.; Gun’ko, Y.; Jacob, K.; Edelmann, F. T. Coord.
Chem. ReV. 2000, 206-207, 321-368. (f) Duchateau, R. Chem. ReV. 2002,
102, 3525-3542. (g) Hanssen, R. W. J. M.; van Santen, R. A.; Abbenhuis,
H. C. L. Eur. J. Inorg. Chem. 2004, 675-683. (h) Lorenz, V.; Edelmann,
F. T. Z. Anorg. Allg. Chem. 2004, 630, 1147-1157.
Results and Discussion
The reaction of silsesquioxanes R7Si7O9(OH)3 (R ) cyclo-
C5H9, iso-C4H9) with trans-[PtI(Ph)(L)2] (L ) PEt3, PMe2Ph)
in the presence of Ag2O produces platinum complexes with
monodentate silsesquioxane ligands, trans-[Pt{O10Si7R7(OH)2}-
(Ph)(L)2] (1a: R ) cyclo-C5H9; L ) PEt3, 1b: R ) iso-C4H9;
L ) PEt3, 2a: R ) cyclo-C5H9; L ) PMe2Ph, 2b: R ) iso-
C4H9; L ) PMe2Ph), at room temperature, shown by eq 1. The
31P{1H} NMR spectra of the reaction mixture indicate that the
completion of the metathesis reaction requires 24-120 h. The
(3) Mayer, J. M. Comments Inorg. Chem. 1988, 8, 125-135.
(4) (a) Wada, K.; Yamada, K.; Kondo, T.; Mitsudo, T. Chem. Lett. 2001,
12-13. (b) Wada, K.; Itayama, N.; Watanabe, N.; Bundo, M.; Kondo, T.;
Mitsudo, T. Organometallics 2004, 23, 5824-5832. (c) Edelmann, F. T.;
Giessmann, St.; Fischer, A. J. Organomet. Chem. 2001, 620, 80-89.
(5) (a) Wada, K.; Izuhara, D.; Shiotsuki, M.; Kondo, T.; Mitsudo, T.
Chem. Lett. 2001, 734-735. (b) van der Vlugt, J. I.; Fioroni, M.; Ackerstaff,
J.; Hanssen, R. W. J. M.; Mills, A. M.; Spek, A. L.; Meetsma, A.;
Abbenhuis, H. C. L.; Vogt, D. Organometallics 2003, 22, 5297-5306. (c)
van der Vlugt, J. I.; Ackerstaff, J.; Dijkstra, T. W.; Mills, A. M.; Kooijman,
H.; Spek, A. L.; Meetsma, A.; Abbenhuis, H. C. L.; Vogt, D. AdV. Synth.
Catal. 2004, 346, 399-412.
(7) Quadrelli, E. A.; Davies, J. E.; Johnson, B. F. G.; Feeder, N. Chem.
Commun. 2000, 1031-1032.
(8) (a) Fukuoka, A.; Sato, A.; Mizuho, Y.; Hirano, M.; Komiya, S. Chem.
Lett. 1994, 1641-1644. (b) Fukuoka, A.; Sato, A.; Kodama, K.; Hirano,
M.; Komiya S. Inorg. Chim. Acta 1999, 294, 266-274.
(9) Mintcheva, N.; Nishihara, Y.; Mori, A.; Osakada, K. J. Organomet.
Chem. 2001, 629, 61-67.
(6) Abbenhuis, H. C. L.; Burrows, A. D.; Kooijman, H.; Lutz, M.; Palmer,
M. T.; van Santen, R. A.; Spek, A. L. Chem. Commun. 1998, 2627-2628.
(10) Mintcheva, N.; Nishihara, Y.; Tanabe, M.; Hirabayashi, K.; Mori,
A.; Osakada, K. Organometallics 2001, 20, 1243-1246.
10.1021/om060192s CCC: $33.50 © 2006 American Chemical Society
Publication on Web 06/16/2006

New Phenylplatinum Complexes Containing Silsesquioxane
Organometallics, Vol. 25, No. 15, 2006 3777
Table 1. Selected Bond Distances (Å) and Angles (deg) of 1a
and 1b
platinum-silsesquioxane complexes 1a, 1b, and 2a were
obtained in high yields (74-98%), although the isolated yield
of 2b is much lower (5%) owing to the high solubility of 2b in
organic solvents.
1a
1b
Pt-P1
2.303(1)
2.309(1)
2.129(3)
2.014(4)
2.558(4)
4.104(5)
2.750(5)
1.84(6)
2.297(1)
2.304(1)
2.113(2)
1.998(3)
2.547(4)
4.143(3)
2.757(4)
1.92(5)
Pt-P2
Pt-O1
Pt-C1
O1‚‚‚O6
O1‚‚‚O7
O6‚‚‚O7
O1‚‚‚H1
O6‚‚‚H2
2.13(5)
2.04(5)
P1-Pt-O1
P1-Pt-C1
P2-Pt-O1
P2-Pt-C1
Pt-O-Si
O1‚‚‚H1-O6
O6‚‚‚H2-O7
92.02(8)
88.5(1)
92.70(9)
86.6(1)
134.6(2)
172(5)
92.55(8)
87.5(1)
92.05(8)
87.9(1)
130.2(2)
165(5)
175(2)
167(5)
Figure 1a shows the molecular structure of 1a determined
by X-ray crystallography. The selected bond distances and
angles of 1a and 1b are summarized in Table 1. Both complexes
1a and 1b have square-planar Pt(II) centers with two phosphine
ligands at trans coordination sites. The Pt-O1 bond distances
of 1a (2.129(3) Å) and 1b (2.113(2) Å) are longer than the Pt-O
bond distances of the platinum complexes with bidentate
silsesquioxane ligands, [Pt{O11Si7(cyclo-C5H9)7(OSiMe3)}-
(dppe)] (dppe ) bis(1,2-diphenylphosphino)ethane) (2.031(6),
2.036(4) Å)6 and [Pt{O11Si7(cyclo-C5H9)7(OSiMe3)}(η4-C8H12)]
(1.987(5), 1.990(5) Å),7 and those of siloxoplatinum complexes
PtEt(OSiPh3)(cod) (2.003(4) Å), PtPh(OSiPh3)(cod) (1.992(3)
Å),8 and trans-[Pt{OSiMe2(C6H4CF3-4)}(Ph)(PPh3)2] (2.091-
(4) Å).9 A large trans influence of the phenyl ligand and the
electron-withdrawing effect of the silsesquioxane moiety2a
elongate the Pt-O bond of 1a and 1b. The phosphine ligands
at the cis positions of the silsesquioxane ligand also affect Pt-O
bond distances. The complexes have decreasing bond distances
in the order 1a > 1b > trans-[Pt{OSiMe2(C6H4CF3-4)}(Ph)-
(PPh3)2]; the complex with more electron-donating phosphine
ligands contains longer a Pt-O bond of the siloxo and
silsesquioxane ligands.
The O1‚‚‚O6 and O6‚‚‚O7 distances of 1a (2.558(4), 2.750-
(5) Å) are within the range of the O‚‚‚H-O hydrogen bond
lengths. Actually, O6-H1 and O7-H2 bonds are directed
toward oxygen atoms, namely, O1 and O6, respectively. The
Si-OH groups of 1b also form two intramolecular hydrogen
bonds. The presence of hydrogen bonding is consistent with an
almost linear O‚‚‚H-O arrangement, O1‚‚‚H1-O6 (1a: 172-
(5)°, 1b: 165(5)°) and O6‚‚‚H2-O7 (1a: 175(2)°, 1b: 167-
(5)°) as well as O1‚‚‚H1 (1a: 1.84(6) Å, 1b: 1.92(5) Å) and
O6‚‚‚H2 (1a: 2.13(5) Å, 1b: 2.04(5) Å), distances within the
sum of the van der Waals radii for H and O atoms (2.72 Å).11
The O‚‚‚O and O‚‚‚H distances of O1‚‚‚H1-O6 are shorter than
those of O6‚‚‚H2-O7, indicating that the former hydrogen
bonds between the OH group and coordinated oxygen are
stronger than the latter between two OH groups of the ligand.
Ott et al. have reported a similar intramolecular hydrogen bond
of iron silsesquioxane complexes (O‚‚‚H-O angle: 172.7°,
O‚‚‚H distance: 1.947 Å).12 Fluoroalkoxide and arylalkoxide
complexes of Rh, Pd, Pt, and Ru were reported to form a 1:1
aggregate with alcohols through a strong O‚‚‚H-O bond
between the alcohol and the alkoxide ligand in the solid state
and in solution.13-16
1
The H NMR spectra of 1 and 2 exhibit signals for OH
hydrogens of the silsesquioxane ligand at low magnetic field
(11) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(12) Liu, F.; John, K. D.; Scott, B. L.; Baker, R. T.; Ott, K. C.; Tumas,
W. Angew. Chem., Int. Ed. 2000, 39, 3127-3130.
(13) Kegley, S. E.; Schaverien, C. J.; Freudenberger, J. H.; Bergman,
R. G.; Nolan, S. P.; Hoff, C. D. J. Am. Chem. Soc. 1987, 109, 6563-6565.
(14) (a) Braga, D.; Sabatino, P.; Bugno, C. D.; Leoni, P.; Pasquali, M.
J. Organomet. Chem. 1987, 334, C46-C48. (b) Bugno, C. D.; Pasquali,
M.; Leoni, P.; Sabatino, P.; Braga, D. Inorg. Chem. 1989, 18, 1390-1394.
(15) (a) Osakada, K.; Kim, Y.-J.; Yamamoto, A. J. Organomet. Chem.
1990, 382, 303-317. (b) Kim, Y.-J.; Osakada, K.; Takenaka, A.; Yamamoto,
A. J. Am. Chem. Soc. 1990, 112, 1096-1104. (c) Osakada, K.; Kim, Y.-J.;
Tanaka, M.; Ishiguro, S.; Yamamoto, A. Inorg. Chem. 1991, 30, 197-
200. (d) Osakada, K.; Ohshiro, K.; Yamamoto, A. Organometallics 1991,
10, 404-410. (e) Kim, Y.-J.; Lee, J. Y.; Osakada, K. J. Organomet. Chem.
1998, 558, 41-49.
Figure 1. ORTEP drawings of 1a (a) and 3a (b) at 50% and 30%
ellipsoidal level, respectively. Hydrogens atoms and cyclopentyl
substituents attached to Si atoms are omitted for simplicity.

3778 Organometallics, Vol. 25, No. 15, 2006
MintcheVa et al.
Scheme 2
Scheme 3
Figure 2. Variable-temperature 1H NMR spectra of 1a in toluene-
d8 at (i) -80 °C, (ii) -50 °C, (iii) 0 °C, and (iv) 25 °C.
(δ 8.5-9.2). The low magnetic field positions of the signals
are ascribed to the O-H‚‚‚O hydrogen bonding that is observed
by X-ray crystallography. The 1H NMR spectrum of [(c-C6H11)7-
Si7O11(OH)SnII]2 was also reported to show the OH hydrogen
signal at low-field position, although it was explained by O-H‚
‚‚Sn interaction.17 The addition of D2O to an NMR sample in
C6D6 causes the disappearance of the OH hydrogen signal
because of the rapid exchange of hydroxo protons with D2O. A
variable-temperature 1H NMR study of these complexes revealed
Scheme 4
1
their dynamic behavior in solution. The H NMR spectrum of
1a in toluene-d8 at -80 °C (Figure 2 (i)) is consistent with the
Cs symmetry of the molecule. The crystal structures of 1a and
1
1b show two different OH hydrogens, whereas the H NMR
spectra in solution at -80 °C exhibit a single OH hydrogen
peak (1a: δ 9.15, 1b: δ 9.48) probably because of the rapid
exchange of the two OH hydrogens, shown in Scheme 1.
ring is perpendicular to the coordination plane, as found by
X-ray crystallography (Figure 1a). On increasing the tempera-
ture, 1H NMR signals of the ortho protons of the phenyl ligand
are broadened at 0 °C and completely coalesce at 25 °C, as
shown in Figure 2 (ii)-(iv). Scheme 3 depicts two possible
dynamic behaviors that account for change of the NMR spectra
depending on temperature. Rapid rotation of the platinum-aryl
bond renders two ortho hydrogens of the phenyl ligand
magnetically equivalent, as shown in Scheme 3 (i). NMR study
of a cis-platinum iodo complex with a chelating diphosphine
ligand revealed the rotation of the Pt-C bond on the NMR
scale.18 Intramolecular exchange of O-Pt and O-H bonds,
including activation of both Pt-O1 and O6-H1 bonds and the
concurrent formation of Pt-O6 and H1-O1 (Scheme 3 (ii)),
also causes the coalescence of the signals. Late-transition metal
alkoxide complexes with associated alcohol through hydrogen
bonding cause the intramolecular exchange of an alkoxide ligand
and alcohol on the NMR time scale (Scheme 4).13-16 Thus,
either rotation of the Pt-aryl bond or intramolecular exchange
of the platinum group between the siloxo ligand and silanol is
responsible for the temperature-dependent change of the NMR
spectra.
Scheme 1
Structure A contains a hydrogen bond between H1 and the
coordinated oxygen (O1) as well as that between silanol oxygen
(O6) and H2. The switching of the hydrogen bond forms
structure B, having hydrogen bonds between O1 and H2 and
between O7 and H1. Another possible explanation for a single
OH hydrogen signal may be a structure of the complex with
symmetrically bifurcated hydrogen bonds between coordinated
oxygen and the two Si-O-H groups, as shown in Scheme 2.
However the bifurcated interactions are not consistent with the
crystal structure of 1a or 1b.
Two peaks at δ 7.57 and 7.37 (Figure 2 (i)) are assigned to
the ortho hydrogens of the phenyl ligand whose six-membered
The IR spectra of 1a, 1b, and 2a in the solid state show a
broad absorption at 3300-3200 cm-1, which is assigned as the
stretching vibration of the OH bond involved in the O‚‚‚H-O
hydrogen bond system. C-H stretching vibrations (2953-2865
cm-1) and strong Si-O broad bands (centered at 1150-1100
(16) (a) Alsters, P. L.; Baesjou, P. J.; Janssen, M. D.; Kooijman, H.;
Sicherer-Roetman, A.; Spek, A. L.; van Koten, G. Organometallics 1992,
11, 4124-4135. (b) Kapteijn, G. M.; Dervisi, A.; Grove, D. M.; Kooijman,
H.; Lakin, M. T.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1995, 117,
10939-10949.
(17) Duchateau, R.; Dijkstra, T. W.; Severn, J. R.; van Santen, R. A.;
Korobkov, I. V. Dalton Trans. 2004, 2677-2682.
(18) Brown, J. M.; Perez-Torrente, J. J.; Alcock, N. W. Organometallics
1995, 14, 1195-1203.

New Phenylplatinum Complexes Containing Silsesquioxane
Organometallics, Vol. 25, No. 15, 2006 3779
cm-1) are observed at normal positions for silsesquioxane.19
A
Table 2. Selected Bond Distances (Å) and Angles (deg) of 3a
and 3b
new band at approximately 740 cm-1 is observed and assigned
to the Si-O group bonded to platinum, in agreement with a
monodentate-coordinated silsesquioxane.
3a
3b
Pt-P2
2.200(3)
2.042(8)
2.15(1)
1.95(2)
2.316(3)
2.161(8)
3.151(2)
2.61(1)
3.25(2)
2.53(1)
2.192(2)
2.076(5)
2.141(6)
2.01(1)
2.327(2)
2.142(5)
3.0875(7)
2.572(6)
3.167(8)
2.534(8)
The 31P{1H} NMR spectra of 1 and 2 show a single signal
of phosphine ligands, and the coupling constants (JPPt ) 2860-
2956 Hz) suggest the trans position of the ligands of the square-
planar Pt(II) center. The 13C{1H} NMR spectra of 1a, 1b, and
2a contain five signals for the seven CH carbon atoms of the
cyclopentyl groups (1a and 2a) or CH2 carbon atoms of the
isobutyl substituents (1b) in 1:2:2:1:1 ratio. The 29Si{1H} NMR
spectra of complexes 1a, 1b, and 2a at room temperature in
solution display five signals in the ratio 2:1:1:1:2 for the seven
silicon atoms in the silsesquioxane framework. The number and
relative intensity of the peaks are consistent with the rapid
exchange of the OH group in solution, shown in Scheme 1.
Two pairs of magnetically equivalent Si nuclei, (Si2 and Si3)
and (Si5 and Si6) in Figure 1a, show the NMR signals at δ
-67.68 and -56.65, respectively. A signal at δ -57.67 is
assigned to a Si nucleus that is bonded to coordinated oxygen.
The 29Si NMR spectra of the complexes 1a, 1b, and 2a often
exhibited a minor peak due to contamination with completely
condensed cubic silsesquioxanes (cyclo-C5H9)Si8O12 or (iso-
C4H9)Si8O12 (δ -65.4 for 1a and 2a, δ -66.8 for 1b).20 The
removal of the impurity from 2a and 2b is difficult owing to
the similar solubility of the complexes and cubic silsesquioxane,
and sufficient elemental analyses were not achieved.
Pt-O1
Pt-O2
Pt-C1
Ag-P1
Ag-O1
Pt‚‚‚Ag
Ag‚‚‚O5
O1‚‚‚O5
O2‚‚‚O5
P2-Pt-O2
P2-Pt-C1
O1-Pt-O2
O1-Pt-C1
P1-Ag-O1
Pt-O1-Ag9
Pt-O1-Si1
Pt-O2-Si2
Si4-O5-O1
Si4-O5-Ag
Si4-O5-O2
95.5(2)
90.1(3)
84.4(4)
90.0(5)
166.0(3)
7.1(3)
136.6(5)
124.1(5)
101.4(4)
101.1(4)
122.7(4)
98.5(2)
88.5(2)
84.2(2)
88.9(2)
168.6(2)
94.1(2)
133.0(3)
126.1(3)
105.1(3)
111.4(3)
118.9(3)
center is bonded to one of the coordinated oxygen atoms and
PPh3 to form a linear coordination (P1-Ag-O1, 3a: 166.0-
(3)°, 3b: 168.6(2)°). The distances between Pt and Ag atoms
(3a: 3.151(2) Å, 3b: 3.0875(7) Å) are longer than the sum of
the atomic radii of Pt and Ag (2.83 Å) and that of the dative
bond between Pt(II) and Ag(I) reported (2.6781(9)-2.8121(9)
Å),21 indicating the absence of a metal-metal bond in 3a and
3b. The Ag-P1 bond distances of the complexes (3a: 2.316-
(3) Å, 3b: 2.327(2) Å) are shorter than those of the linear Ag-
(I)-PPh3 complexes [AgNO3(PPh3)] (2.369 Å)22 and [AgCl-
(PPh3)]4 (2.382 Å).23 Although the positions of OH hydrogens
in 3a and 3b are not determined by crystallography, a short
contact between O2 and O5 atoms (3a: 2.53(1) Å, 3b: 2.534-
(8) Å) suggests an O-H‚‚‚O hydrogen bond between the OH
group and coordinated oxygen. A short Ag‚‚‚O5 distance (3a:
2.61(1) Å, 3b: 2.572(6) Å) is also observed.24 The IR spectra
of 3a and 3b in the solid state show OH peaks as weak, broad
absorptions at slightly higher wavenumbers (3450 cm-1) than
those of monodentate platinum silsesquioxanes 1a, 1b, and 2a
(3300-3200 cm-1). These values are in the range reported by
Dijkstra et al. for mono-hydrogen-bonded and poly-hydrogen-
Reactions of the silsesquioxanes with trans-[PtI(Ph)(PPh3)2]
in the presence of Ag2O at 55 °C yield a mixture of unexpected
Pt-Ag heterobimetallic silsesquioxane complexes, [Pt{O11Si7R7-
(OH)(AgPPh3)}Ph(PPh3)] (3a: R ) cyclo-C5H9, 3b: R ) iso-
C4H9), and a hydroxo-bridged platinum dimer, anti-[{PtPh-
(PPh3)}2(µ-OH)2] (4), as shown in eq 2. The 31P{1H} NMR
spectrum of the reaction mixture displays a 2:1 ratio of 3 to 4.
Complexes 3a and 3b were isolated from the reaction mixture
in 47% and 39% yields, respectively.
1
bonded silanols, respectively.25 The H NMR spectrum of 3a
in toluene-d8 at -50 °C exhibits a signal of an OH group at a
low magnetic field (δ 12.82) due to strong O-H‚‚‚O bonding
or O-H‚‚‚Ag interaction.
Figure 3 shows the 31P{1H} NMR spectrum of 3a, which
displays two signals assigned to the two phosphorus atoms
bonded to Pt and to Ag based on the coupling patterns with
195Pt and 107+109Ag nuclei. 3a and 3b show large 31P-195Pt
coupling constants (4945 and 4939 Hz). The resonance for the
phosphorus atom coordinated to the Ag center of 3a and 3b is
observed as two doublets because of coupling with two magnetic
isotopes 107Ag and 109Ag (3a: JP107Ag ) 679 Hz, JP109Ag ) 784
Hz, 3b: JP107Ag ) 682 Hz, JP109Ag ) 787 Hz) at room
The formation of 3a and 3b with a chelating silsesquioxane
ligand and a PPh3 ligand rather than a Ag-free platinum complex
with monodentate silsesquioxane and two PPh3 ligands is partly
ascribed to the facile dissociation of PPh3 prior to or during the
reaction, while PEt3 and PMe2Ph ligands in eq 1 do not undergo
dissociation easily.
Figure 1b shows the molecular structure of 3a determined
by X-ray crystallography. The selected bond distances and
angles of 3a and 3b are summarized in Table 2. A square-planar
Pt(II) center is bonded to a phenyl ring, one PPh3 ligand, and
two oxygen atoms of the deprotonated silsesquioxane. A Ag
(21) Yamaguchi, T.; Yamazaki, F.; Ito, T. J. Am. Chem. Soc. 2001, 123,
743-744.
(22) Stein, R. A.; Knobler, C. Inorg. Chem. 1977, 16, 242-245.
(23) Teo, B.-K.; Calabrese, J. C. Inorg. Chem. 1976, 15, 2467-2474.
(24) Wang, R.; Hong M.; Luo, J.; Jiang, F.; Han, L.; Lin, Zh.; Cao, R.
Inorg. Chim. Acta 2004, 357, 103-114.
(25) (a) Dijkstra, T. W.; Duchateau, R.; van Santen, R. A.; Meetsma,
A.; Yap, G. P. A. J. Am. Chem. Soc. 2002, 124, 9856-9864. (b) Duchateau,
R.; Dijkstra, T. W.; van Santen, R. A.; Yap, G. P. A. Chem. Eur. J. 2004,
10, 3979-3990.
(19) Davidova, I. E.; Gribov, L. A.; Maslov, I. V.; Dufaud, V.; Niccolai,
G. P.; Bayard, F.; Basset, J. M. J. Mol. Struct. 1998, 443, 89-106.
(20) Bassindale, A. R.; Liu, Zh.; MacKinnon, I. A.; Taylor, P. G.; Yang,
Y.; Light, M. E.; Horton, P. N.; Hursthouse, M. B. Dalton Trans. 2003,
2945-2949.

3780 Organometallics, Vol. 25, No. 15, 2006
MintcheVa et al.
Figure 4. ORTEP drawing of 4 at 50% ellipsoidal level. Hydrogens
except for OH hydrogens are omitted for simplicity. The molecule
has a C2 symmetry center at the midpoint of two Pt centers. Atoms
with asterisks are crystallographically equivalent to those having
the same number without asterisks. The selected bond distances
(Å) and angles (deg) of 4 are as follows: Pt-P 2.198(2), Pt-O
2.069(6), Pt-O* 2.113(6), Pt-C1 2.004(6), P-Pt-O* 96.6(2),
P-Pt-C1 95.7(2), O-Pt-O* 76.5(2), O-Pt-C1 91.3(2).
Figure 3. 31P{1H} NMR spectrum of 3a in C6D6 at room
temperature.
temperature, although PPh3 coordinated to Ag(I) often shows a
broad peak due to the facile dissociation of the ligand from the
labile d10 center.26 Pt-Ag binary complexes with bridging
alkynyl ligands [Pt(C6F5)2(µ-CtCPh)2Ag(PPh3)](NBu4) (JP107Ag
) 570 Hz, JP109Ag ) 657 Hz at -60 °C)27 or a bridging
hydrosulfido ligand [Pt(C6F5)2(PPh3){S(H)Ag(PPh3)}] (JP107Ag
) 570 Hz, JP109Ag ) 657 Hz at -50 °C)28 show smaller coupling
constants than 3a and 3b with bridging siloxo ligands at low
temperatures. A strong coordination of PPh3 to the Ag(I) center
of 3a and 3b is evidenced also by short AgP bonds in the
crystallographic results.
The 29Si{1H} NMR spectra of 3a and 3b exhibit signals
corresponding to seven silicon atoms in their molecules. Four
signals at higher magnetic field (δ -65.28, -65.56, -66.73,
and -67.20 for 3a, and -66.86, -66.92, -68.13, and -69.00
for 3b) are assigned as the internal Si atoms of the silsesquioxane
framework, while three signals, at δ -55.84, -56.62, -58.24
(3a) and -57.60, -57.95, -59.20 (3b), are due to the terminal
Si atoms of the silsesquioxane. The signals at -55.84 and
-57.95 are split by coupling with a Ag nucleus (4.8 Hz (3a)
and 2 Hz (3b)).29 In the 13C{1H} NMR spectra of 3a and 3b,
the Si-C carbon atoms in the silsesquioxane framework show
seven signals in the range δ 23.08-25.60. The IR spectra of
3a and 3b show two new bands due to the stretching vibration
Si-O of coordinated silanol groups at lower frequencies (695,
745 (3a) and 694, 739 cm-1 (3b)) in comparison with those of
free ligands.
ratio of 3a (or 3b) to 4, indicating that the hydrolysis of the Pt
complex during reaction 2 produces 4. A similar reaction of a
Pt(II) complex, [PtBr(PEt3)3](BF4), with silanol (4-CF3C6H4)-
SiMe2OH in the presence of Ag2O also gives a hydroxo-bridged
diplatinum complex, [Pt2(µ-OH)2(PEt3)4](BF4)2, upon the ad-
dition of H2O.10 The crystal structure of 4, which is isomorphous
to the palladium dimer [{PdPh(PPh3)}2(µ-OH)2],32 is determined
by X-ray crystallography (Figure 4). The geometry around the
Pt center consists of a phenyl, a PPh3, and two bridging hydroxo
groups. The short distance of the Pt-P bond of 4 (2.198(2) Å)
is consistent with the large coupling constant between Pt and P
atoms (4687 Hz), which is similar to that of the hydroxo-bridged
platinum dimer trans-[{Pt(C6H4Me-4)(PEt2Ph)}2(µ-OH)2] (JPPt
) 4425 Hz).33
Conclusion
Incompletely condensed silsesquioxane functions as a mono-
dentate ligand of a neutral phenylplatinum complex and as a
bidentate ligand of phenylplatinate with one phosphino ligand
and AgPPh3 that is bonded to coordinated oxygen depending
on the type of phosphine ligand. Two types of platinum
complexes with incompletely condensed silsesquioxane were
obtained depending on auxiliary phosphine ligands. The sils-
esquioxane functions as a monodentate ligand of the neutral
phenylplatinum complexes trans-[Pt{O10Si7R7(OH)2}(Ph)(L)2]
with two PEt3 or PPhMe2 groups in mutually trans positions.
The phenylplatinate [Pt{O11Si7R7(OH)(AgPPh3)}(Ph)(PPh3)]
with a PPh3 ligand contains the bidentate silsesquioxane ligand
in which an oxygen atom is bonded both to the Pt center and to
the AgPPh3 fragment. Facile dissociation of PPh3 from the Pt
center induced chelating coordination of the silsesquioxane, to
form the platinate with Ag(I).
A hydroxo-bridged organoplatinum dimer, 4, obtained from
reaction 2 was reported to be synthesized in situ from [PtPh-
(PPh3)(µ-Cl)]2 and KOH.30 The NMR spectroscopic data of 4
obtained in reaction 2 are completely consistent with those of
the dinuclear platinum complex prepared independently from
the thermal reaction of trans-[PtPh(OH)(PPh3)2].31 In reaction
2, the addition of an equivalent amount of H2O leads to a 1:4
(26) (a) Muetterties, E. L.; Alegranti, C. W. J. Am. Chem. Soc. 1972,
94, 6386-6391. (b) Carmona, D.; Ferrer, J.; Lamata, M. P.; Oro, L. A.;
Limbach, H.-H.; Scherer, G.; Elguero, J.; Jimeno, M. L. J. Organomet.
Chem. 1994, 470, 271-274.
Experimental Section
(27) Fornie´s, J.; Lalinde, E.; Mart´ınez, F.; Moreno, M. T.; Welch, A. J.
J. Organomet. Chem. 1993, 455, 271-281.
General Procedures. All manipulations of the complexes were
carried out using standard Schlenk techniques under argon or
nitrogen atmosphere. Toluene for reactions was distilled from
sodium benzophenone ketyl and stored under nitrogen. The platinum
(28) Ruiz, J.; Rodriguez, V.; Vicente, C.; Marti, J. M.; Lopez, G.; Perez,
J. Inorg. Chem. 2001, 40, 5354-5360.
(29) Schwenk, A.; Piantini, U.; Wojnowski, W. Z. Naturforsch. 1991,
46a, 939-946.
(30) Grushin, V. V.; Bensimon, C.; Alper, H. Organometallics 1993,
12, 2737-2740.
(32) Grushin, V. V.; Alper, H. Organometallics 1993, 12, 1890-1901.
(33) Fakley, M. E.; Pidcock, A. J. Chem. Soc., Dalton Trans. 1977,
1444-1448.
(31) Yoshida, T.; Okano, T.; Otuska, S. J. Chem. Soc., Dalton Trans.
1976, 993-999.

New Phenylplatinum Complexes Containing Silsesquioxane
Organometallics, Vol. 25, No. 15, 2006 3781
complexes trans-[PtI(Ph)(PEt3)2], trans-[PtI(Ph)(PPhMe2)2], and
trans-[PtI(Ph)(PPh3)2] were prepared by replacement of cod (1,5-
cyclooctadiene) from [PtI(Ph)(cod)] with corresponding phosphine
ligands, as previously reported.34 The complex [PtI(Ph)(cod)] was
synthesized according to the literature method.35 Silsesquioxanes
1,3,5,7,9,11,14-heptacyclopentyltricyclo[7.3.3.1(5,11)]heptasiloxane-
endo-3,7,14-triol ((cyclo-C5H9)7Si7O9(OH)3) and 1,3,5,7,9,11,14-
heptoisobutyltricyclo[7.3.3.1(5,11)]heptasiloxane-endo-3,7,14-tri-
ol ((iso-C4H9)7Si7O9(OH)3) are commercial available products of
Aldrich Chemical Co. Ag2O was purchased from Wako Pure
Chemical Ind., Ltd. The reagents are used without any purification.
1H, 13C{1H}, 29Si{1H}, and 31P{1H} NMR spectra were recorded
on Varian Mercury 300 or JEOL EX-400 spectrometers. Peak
positions in the 29Si{1H} and 31P{1H} NMR spectra were referenced
to external standard SiMe4 in C6D6 and 85% H3PO4 in C6D6,
respectively. To minimize nuclear Overhauser enhancement effects,
29Si NMR spectra were recorded with inverse-gated proton decou-
pling. IR absorption spectra were recorded on a Shimadzu FT/IR-
8100 spectrometer. Elemental analyses were carried out with a
Yanaco MT-5 CHN autocorder.
solution gave 1b as colorless crystals in 76% yield (148 mg). Anal.
Calcd for C46H100O12P2Si7Pt: C, 42.54; H, 7.76. Found: C, 42.31;
H, 7.62. Mp: 86 °C. 1H NMR (300 MHz, benzene-d6, room
temperature): δ 0.89 (d, 14H, CH2-iBu, JHH ) 7.2 Hz), 1.03 (vt,
18H, PCH2CH3, VJCP ) 8.0 Hz), 1.14 (d, 6H, CH3-iBu, JHH ) 6.6
Hz), 1.15 (d, 6H, CH3-iBu, JHH ) 6.6 Hz), 1.19 (d, 24H, CH3-iBu,
JHH ) 6.6 Hz), 1.26 (d, 6H, CH3-iBu, JHH ) 6.6 Hz), 1.49 (br, 12
H, PCH2CH3), 2.21 (m, 7H, CH-iBu, JHH ) 6.6 Hz), 6.94 (m, 3H,
C6H5 meta and para), 7.41 (s, 2H, C6H5-o, JHPt was not observed
1
clearly), 8.84 (s, 2H, OH). H NMR (400 MHz, toluene-d8, -80
°C): δ 0.97 (br, 14H, CH2-iBu), 1.08 (br, 18H, PCH2CH3), 1.2-
1.5 (m, 54H, CH3-iBu and PCH2CH3), 2.31 (m, 7H, CH-iBu), 7.38
(s, 1H, C6H5 ortho), 7.54 (s, 1H, C6H5 ortho), 9.48 (s, 2H, OH).
Signals for C6H5 meta and para are overlapped with solvent. 13C-
{1H} NMR (75 MHz, benzene-d6, room temperature): δ 7.58 (s,
V
PCH2CH3), 12.73 (vt, PCH2CH3, JPC ) 16.1 Hz,), 23.24, 23.37,
23.98, 24.19, 27.37 (1:1:2:2:1, 7C, CH2)*, 24.55, 24.60, 24.63,
25.52 (7C, CH)*, 25.91, 25.97, 26.03, 26.23, 26.32, 26.52 (14C,
CH3)*, 122.36 (C6H5 meta), 127.85 (C6H5 para), 131.21 (t, C6H5
2
ipso, JCP ) 9.8 Hz,), 137.63 (C6H5 ortho). *Chemical shifts for
CH, CH2, CH3 carbon atoms originated from iso-butyl groups were
determined by the DEPT method. 29Si{1H} NMR (79 MHz,
benzene-d6, 0.02 M Cr(acac)3, room temperature): δ -57.42,
-57.97, -65.80, -66.11, -68.80 (2:1:1:1:2). 31P{1H} NMR (122
MHz, benzene-d6, room temperature): δ 17.3 (JPtP ) 2860 Hz).
IR (KBr): 3300 (vw), 2953 (s), 2907 (s), 2874 (s), 1464 (w), 1229
(m), 1100 (s), 908 (w), 835 (w), 768 (w), 739 (m), 710 (w), 486
Preparation of trans-[Pt{O10Si7(cyclo-C5H9)7(OH)2}(Ph)-
(PEt3)2] (1a). To a toluene (10 mL) solution of trans-[PtI(Ph)-
(PEt3)2] (95 mg, 0.15 mmol) were added (cyclo-C5H9)7Si7O9(OH)3
(131 mg, 0.15 mmol) and Ag2O (46 mg, 0.20 mmol). The mixture
was stirred for 3 days at room temperature. After completion of
the reaction, monitored with 31P{1H} NMR spectroscopy, a gray
solid was removed by filtration through Celite. Complete evapora-
tion of the solvent from the filtrate gave 1a as a white solid (204
mg, 98%). Slow diffusion of acetone in toluene solution of 1a
affords colorless crystals appropriate for X-ray analysis. When the
reaction was performed at 55 °C, complex 1a was obtained as a
major product, accompanied by uncharacterized side compounds.
No signal for heterobimetallic Pt-Ag complex analogous to 3a
was observed. Anal. Calcd for C53H100O12P2Si7Pt: C, 46.03; H,
7.29. Found: C, 45.89; H, 6.79. Mp: 164 °C. 1H NMR (300 MHz,
benzene-d6, room temperature): δ 1.07 (m, 18H, PCH2CH3), 1.22
(br m, 7H, CH-pentyl), 1.5-2.4 (br m, 68H, CH2-pentyl and PCH2-
CH3), 6.94 (m, 3H, C6H5 meta and para), 7.41 (s, 2H, C6H5 ortho,
(m) cm-1
.
Preparation of trans-[Pt{O10Si7(cyclo-C5H9)7(OH)2}(Ph)-
(PPhMe2)2] (2a). Preparation of 2a was carried out similarly from
trans-[PtI(Ph)(PMe2Ph)2] (101 mg, 0.15 mmol), (cyclo-C5H9)7Si7O9-
(OH)3 (131 mg, 0.15 mmol), and Ag2O (46 mg, 0.20 mmol) in
toluene (10 mL). The reaction mixture was stirred at room
temperature for 5 days. The product 2a was obtained by recrys-
tallization from ether/ethanol solution at -20 °C in 74% yield (158
mg). Mp: 132 °C. 1H NMR (300 MHz, benzene-d6, room
temperature): δ 1.20 (m, 7H, CH-pentyl), 1.4-2.3 (br m, 68H,
CH2-pentyl and PCH3), 6.6 (br, 2H, PtC6H5 ortho), 6.72 (m, 2H,
PtC6H5 meta), 6.99 (m, 2H, PC6H5 para, JHH ) 7.5 Hz), 7.06 (m,
1
JHPt was not observed clearly), 8.53 (s, 2H, OH). H NMR (400
MHz, toluene-d8, -80 °C): δ 1.10 (br m, 18H, PCH2CH3), 1.2-
2.0 (br m, 75H, CH2-pentyl; CH-pentyl, and PCH2CH3), 7.37 (s,
1H, C6H5 ortho), 7.57 (s, 1H, C6H5 ortho), 9.15 (s, 2H, OH). The
C6H5 meta and para signals are overlapped with solvent. 13C{1H}
NMR (75 MHz, benzene-d6, room temperature): δ 7.64 (s,
4H, PC6H5 meta, JHH ) 7.5 Hz), 7.42 (m, 4H, PC6H5 ortho, JHH
)
1
7.5 Hz), 9.1 (br, 2H, OH). PtC6H5 para signal was not found. H
NMR (400 MHz, toluene-d8, -80 °C): 1.2-2.3 (m, 75H, CH2-
pentyl; CH-pentyl; PCH3), 6.50 (s, 1H, PtC6H5 meta), 6.62 (s, 1H,
PtC6H5 ortho), 6.83 (d, 2H, PtC6H5 meta), 7.35 (s, 1H, PtC6H5
para), 7.42 (s, 4H, PC6H5 ortho), 9.84 (s, 2H, OH). 13C{1H} NMR
(75 MHz, benzene-d6, room temperature): δ 11.8 (br, PCH3), 23.00,
23.14, 23.79, 23.94, 26.60 (1:1:2:2:1, 7C, CH-pentyl), 27.44, 27.55,
27.64, 27.84, 27.97, 28.00, 28.22, 28.26, 28.30, 28.42, 29.64 (28C,
CH2-pentyl), 122.09 (PtC6H5 meta), 127.30 (PtC6H5 para), 128.21
V
PCH2CH3), 12.98 (vt, PCH2CH3, JCP ) 16.4 Hz,), 23.00, 23.08,
23.85, 23.91, 26.74 (1:1:2:2:1, 7C, CH-pentyl), 27.55, 27.58, 27.62,
27.95, 28.26, 28.30, 28.32, 28.34, 29.84 (28C, CH2-pentyl), 122.38
(C6H5 meta), 130.95 (t, 2JCP ) 10.2 Hz, C6H5 ipso), 137.61 (C6H5
ortho). The C6H5 para carbon was not observed due to overlap
with solvent. 29Si{1H} NMR (79 MHz, benzene-d6, 0.02 M Cr-
(acac)3, room temperature): δ -56.65, -57.67, -64.35, -64.69,
-67.68 (2:1:1:1:2). 31P{1H} NMR (122 MHz, benzene-d6, room
temperature): δ 16.5 (JPPt ) 2862 Hz). IR (KBr): 3200 (vw), 2949
(s), 2867 (s), 1508 (w), 1246 (w), 1150 (vs), 922 (m), 878 (m),
V
2
(vt, PC6H5 meta, JCP ) 5.2 Hz), 129.06 (t, PtC6H5 ipso, JCP
)
10.2 Hz), 129.75 (PC6H5 para), 131.37 (vt, PC6H5 ortho, VJCP )5.7
V
Hz), 134.26 (vt, PC6H5 ipso, JCP ) 27.3 Hz), 138.37 (PtC6H5
ortho). 13C{1H} NMR (100.4 MHz, toluene-d8, -70 °C): 9.70 (vt,
V
PCH3, JCP ) 18.6 Hz), 12.19 (vt, PCH3, VJPC ) 18.6 Hz), 22.55,
763 (w), 739 (w), 708 (w), 505 (m) cm-1
.
22.69, 23.51, 23.58, 25.95 (1:1:2:2:1, 7C, CH-pentyl), 27.25, 27.33,
27.39, 27.43, 27.66, 27.82, 28.04, 28.09, 28.33, 29.33, 29.90 (28C,
CH2-pentyl), 121.93 (PtC6H5 meta), 129.75 (PC6H5 para), 131.08
(PC6H5 ortho), 133.64 (vt, PC6H5 ipso, VJCP ) 27 Hz), 137.78 (Pt-
C6H5-o). 29Si{1H} NMR (79.3 MHz, benzene-d6, 0.02 M Cr(acac)3,
room temperature): δ -56.75, -57.30, -64.59, -64.87, -67.60
(2:1:1:1:2). 31P{1H} NMR (122 MHz, benzene-d6, room tempera-
ture): δ -1.3 (JPtP ) 2956 Hz). IR (KBr): 3250 (vw), 2950 (s),
2865 (s), 1450 (w), 1246 (w), 1120 (vs), 945 (w), 907 (m), 741
Preparation of trans-[Pt{O10Si7(iso-Bu)7(OH)2}(Ph)(PEt3)2]
(1b). Complex 1b was synthesized from the reaction of (iso-
Bu)7Si7O9(OH)3 (119 mg, 0.15 mmol) with trans-[PtI(Ph)(PEt3)2]
(95 mg, 0.15 mmol) in the presence of Ag2O (46 mg, 0.2 mmol).
The reaction mixture was stirred at room temperature for 24 h.
After filtration through Celite, washing with toluene, and removing
of the solvent, the crude product was dissolved in 1 mL of acetone
and kept at -20 °C for 2 days. Recrystallization from an acetone
(w), 503 (m) cm-1
.
(34) Kistner, C. R.; Hutchinson, J. H.; Doyle, J. R.; Storlie, J. C. Inorg.
Preparation of trans-[Pt{O10Si7(iso-Bu)7(OH)2}(Ph)(PPhMe2)2]
(2b). Complex 2b was synthesized analogously by using (iso-
Bu)7Si7O9(OH)3 (119 mg, 0.15 mmol) and trans-[PtI(Ph)(PPhMe2)2]
Chem. 1963, 2, 1255-1261.
(35) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411-
428.

3782 Organometallics, Vol. 25, No. 15, 2006
Table 3. Crystallographic Data and Details of Refinement of 1a, 1b, 3a, 3b, and 4
MintcheVa et al.
1a
1b
3a
3b
4
formula
C53H100O12P2Si7Pt
C46H100O12P2Si7Pt
C77H99O12P2Si7Pt
Ag C70H99O12P2Si7Pt‚
1/2C6H14
AgC48H42O2P2Pt2
fw
color
cryst size/mm
cryst syst
space group
a/Å
b/Å
c/Å
R/deg
â/deg
γ/deg
V/Å3
1383.00
colorless
1298.92
colorless
0.22 × 026 × 0.58
triclinic
P1h (No. 2)
13.580(2)
13.659(2)
19.933(3)
71.799(6)
73.423(6)
68.216(6)
3200.8(9)
2
1.348
1356
2.4136
19 756
12 436
0.017
719
0.0385
1778.13
colorless
0.24 × 0.40 × 0.48
monoclinic
Cc (No. 9)
25.810(6)
1737.11
colorless
0.15 × 0.17 × 0.23
monoclinic
P21/n (No.14)
12.784(2)
1102.98
colorless
0.05 × 0.05 × 0.15
monoclinic
P21/n (No.14)
8.792(3)
0.06 × 0.10 × 0.28
monoclinic
P21/c (No. 14)
11.3362(17)
26.444(4)
13.462(3)
24.976(6)
27.027(4)
23.001(4)
14.694(4)
15.298(4)
21.509(3)
91.964(2)
114.184(3)
90.520(3)
100.397(3)
6444(2)
4
1.425
2880
2.4027
47 857
14 542
0.062
782
0.0368
0.1017
0.939
7916(3)
4
1.492
3640
2.2096
29 022
8926
0.070
1035
7947(2)
4
1.453
3576
2.1991
55 875
17 542
0.084
1016
0.0732
0.2217
1.029
1944(1)
2
1.884
1064
7.2828
14 334
4416
0.059
268
Z
D
calcd/g cm-3
F(000)
µ/mm-1
no. of reflns measd
no. of unique reflns
Rint
no. of variables
R1 (I > 2.00σ(I))
wR2 (all data)
GOF
0.0478
0.1375
1.044
0.0346
0.0864
0.943
0.1093
1.063
(101 mg, 0.15 mmol) in the presence of Ag2O (46 mg, 0.2 mmol).
Although the 31P{1H} NMR spectrum of the reaction mixture
displays complete conversion of the starting material after 4 days,
the isolated yield of 2b as a sticky crude product is low (5%) due
131.03 (PtPC6H5 para), 131.17 (d, PtPC6H5 ipso, JCP ) 63 Hz),
131.48 (dd, AgPC6H5 ipso, JCP ) 37 Hz, 2JCAg ) 4.6 Hz), 134.46
2
3
(dd, AgPC6H5 ortho, JCP )16 Hz, JCAg ) 2.9 Hz), 135.34 (d,
2
PtPC6H5 ortho, JCP ) 11 Hz), 138.73 (PtPC6H5 ortho). 29Si{1H}
1
to its high solubility in common organic solvents. H NMR (300
NMR (79.3 MHz, benzene-d6, 0.02 M Cr(acac)3, room tempera-
ture): δ -55.84 (d, JSiAg ) 4.8 Hz), -56.62, -58.24, -65.28,
-65.56, -66.73, -67.20. 31P{1H} NMR (121 MHz, benzene-d6,
MHz, benzene-d6, room temperature): δ 0.84 (m, 14H, CH2-iBu),
1.0-1.2 (m, 54H, CH3-iBu and PCH3), 2.1 (m, 7H, CH-iBu), 6.78
(m, 3H, C6H5 meta and para), 7.02 (m, 6H, PC6H5 meta and para),
7.40 (m, 4H, PC6H5 ortho), 9.2 (br, 2H, OH). 31P{1H} NMR (122
MHz, benzene-d6, room temperature): δ -1.97 (s, JPPt ) 2932
Hz).
room temperature): δ 10.6 (s, JPPt ) 4945 Hz), 15.1 (d, JP107Ag
)
679 Hz, JP109Ag ) 784 Hz). IR (KBr): 3450 (vw), 3052 (w), 2948
(s), 2865 (s), 1437 (s), 1244 (m), 1100 (vs), 970 (m), 912 (m), 745
(m), 695 (s), 524 (s) cm-1
.
Preparation of [Pt{O10Si7(cyclo-C5H9)7(OH)(OAgPPh3)}(Ph)-
(PPh3)] (3a). To a 10 mL toluene suspension of trans-[PtI(Ph)-
(PPh3)2] (138 mg, 0.15 mmol) were added Ag2O (46 mg, 0.20
mmol) and (cyclo-C5H9)7Si7O9(OH)3 (131 mg, 0.15 mmol). This
mixture was then heated for 12 h at 55 °C and gave a mixture of
3a, 4, and Ph3PO. The same products were obtained when the
reaction was carried out for 6 days at room temperature. The
reaction mixture was filtered through Celite to remove the gray
residue. The filtrate was evaporated to afford an oily material.
Complex 3a was separated from 4, Ph3PO, and unreacted silses-
quioxane by addition of ethyl acetate, which caused precipitation
of a white solid. It was filtrated, washed two times with a 1 mL
portion of ethyl acetate, and dried in vacuo to afford complex 3a
(126 mg, 47%). The purification of 4 from the ethyl acetate filtrate
failed. To characterize complex 4, it was prepared by an independent
method, as described below. The single crystals of 3a were prepared
by slow evaporation of a THF/hexane solution at room temperature.
Anal. Calcd for C77H99O12P2Si7PtAg: C, 52.01; H, 5.61. Found:
C, 51.77; H, 5.36. Decomp > 175 °C. 1H NMR (300 MHz,
benzene-d6, room temperature): δ 1.2 (m, 7H, CH-pentyl), 1.5-
2.4 (m, 56H, CH2-pentyl), 6.40 (t, 2H, PtC6H5 meta, JHH ) 7.2
Hz), 6.63 (t, 1H, PtC6H5 para, JHH ) 7.2 Hz), 7.01 (m, 9H, PC6H5
meta and para), 7.10 (m, 11H, PC6H5 meta and para, and PtC6H5
ortho)*, 7.65 (m, 6H, PC6H5 ortho), 7.75 (m, 6H, PC6H5 ortho).
*Peak position of PtC6H5 ortho protons was determined by H-H
COSY. 13C{1H} NMR (75 MHz, benzene-d6, room temperature):
δ 23.08, 23.20, 23.39, 23.88, 24.04, 25.39, 25.60 (1:1:1:1:1:1:1,
7C, CH-pentyl), 27.13, 27.58, 27.78. 27.94, 28.12, 28.23, 28.50,
28.80, 29.64, 27.46, 27.62, 27.84, 28.06, 28.18, 28.39, 28.65, 29.29
(28C, CH2-pentyl), 121.80 (PtC6H5 meta), 127.27 (PtC6H5 para),
127.74 (PtPC6H5 meta), 129.29 (d, AgPC6H5 meta, 3JCP ) 11 Hz),
Preparation of [Pt{O10Si7(iso-Bu)7(OH)(OAgPPh3)}(Ph)-
(PPh3)] (3b). Complex 3b was prepared similarly to 3a using (iso-
Bu)7Si7O9(OH)3 (119 mg, 0.15 mmol). The desired complex was
obtained by recrystallization from acetone solution (1 mL) at -20
°C to yield complex 3b (191 mg, 39%). The reaction of trans-
[PtI(Ph)(PPh3)2] (20 mg, 0.022 mmol) with (iso-C4H9)7Si7O9(OH)3
(17 mg, 0.022 mmol) in the presence of Ag2O (6 mg, 0.029 mmol)
and a stoichiometric amount of H2O (0.4 µL, 0.022 mmol) was
carried out in degassed C6D6 for 12 h at 55 °C. The ratio of the
products was estimated by 31P NMR data. Anal. Calcd for
C70H99O12P2Si7PtAg: C, 49.63; H, 5.89. Found: C, 49.29; H, 6.22.
Mp: 171 °C (dec). 1H NMR (300 MHz, benzene-d6, room
temperature): δ 0.88 (m, 14H, CH2-iBu), 0.98 (d, 6H, CH3-iBu,
JHH ) 6.6 Hz), 1.06 (d, 3H, CH3-iBu, JHH ) 6.6 Hz), 1.14 (m,
24H, CH3-iBu), 1.22 (m, 3H, CH3-iBu), 1.45 (t, 6H, CH3-iBu, JHH
) 6.3 Hz), 1.86 (m, 1H, CH-iBu), 2.03 (m, 1H, CH-iBu), 2.19 (m,
4H, CH-iBu), 2.53 (m, 1H, CH-iBu), 6.45 (t, 2H, PtC6H5 meta,
JHH ) 7.5 Hz), 6.67 (t, 1H, PtC6H5 para, JHH )7.5 Hz), 7.02 (m,
9H, PC6H5 meta and para), 7.11 (m, 11H, PC6H5 meta and para,
and PtC6H5 ortho)*, 7.62 (m, 6H, PC6H5 ortho), 7.74 (m, 6H, PC6H5
ortho). *The signal for PtC6H5 ortho protons was assigned by the
H-H COSY method. 13C{1H} NMR (75.3 MHz, benzene-d6, room
temperature): δ 23.22, 23.46, 23.57, 24.30, 24.42, 24.50, 25.36
(1:1:1:1:1:1:1, 7C, CH2-iBu)*, 24.58, 24.61, 24.66, 24.88, 25.07
(7C, CH-iBu)*, 25.71, 25.90, 25.97, 26.04, 26.07, 26.16, 26.31,
26.36, 26.43, 26.56, 26.71, 27.19 (14C, CH3-iBu)*, 121.95 (PtC6H5
meta), 127.28 (PtC6H5 para), 127.78 (PtPC6H5 meta), 129.33 (d,
AgPC6H5 meta, 3JCP ) 10.4 Hz), 130.17 (AgPC6H5 para), 130.75
(d, PtPC6H5 ipso, JCP ) 63 Hz), 131.08 (PtPC6H5 para), 131.50
2
(dd, AgPC6H5 ipso, JCP ) 32 Hz, JCAg ) 4.6 Hz), 134.43 (dd,
AgPC6H5 ortho, 2JCP ) 16 Hz, 3JCAg ) 2.9 Hz), 135.40 (d, PtPC6H5
4
2
130.13 (d, AgPC6H5 para, JCP ) 2.3 Hz), 130.35 (PtC6H5 ipso),
ortho, JCP ) 10.3 Hz), 138.73 (PtC6H5 ortho). *Chemical shifts

New Phenylplatinum Complexes Containing Silsesquioxane
Organometallics, Vol. 25, No. 15, 2006 3783
for the iBu group were determined by the DEPT method. 29Si{1H}
NMR (79.3 MHz, benzene-d6, 0.02 M Cr(acac)3, room tempera-
ture): δ -57.60, -58.95 (d, JSiAg ) 2 Hz), -59.20, -66.86,
-68.92, -68.13, -69.00. 31P{1H} NMR (122 MHz, benzene-d6,
and φ ) 0.0°. The detector swing angle was -20.42°. A second
sweep was performed using ω-scans from -110.0° to 70.0° in 0.5°
steps, at ø ) 45.0° and φ ) 90.0°. The crystal-to-detector distance
was 44.84 mm. Readout was performed in the 0.070 mm pixel
mode. Calculations were carried out by using the program package
Crystal Structure ver. 3.7 for Windows. A full-matrix least-squares
refinement was used for the nonhydrogen atoms with anisotropic
thermal parameters. One cyclopentyl group bound to Si3 of 3a is
disordered. Two isobutyl groups bound to Si2 and Si6 of 3b were
refined with isotropic thermal parameters. Hydrogen atoms except
for the OH hydrogens of 1a, 1b, and 4 were located by assuming
the ideal geometry and were included in the structure calculation
without further refinement of the parameters. Crystallographic data
and details of refinement are summarized in Table 3.
room temperature): δ 11.0 (JPPt ) 4939 Hz), 14.7 (dd, JP107Ag
)
682 Hz, JP109Ag ) 787 Hz). IR (KBr): 3450 (vw), 3053 (w), 2951
(s), 2866 (m), 1437 (m), 1226 (m), 1098 (vs), 981 (m), 916 (w),
833 (w), 739 (m), 694 (m), 501 (m) cm-1
.
Preparation of anti-[{PtPh(PPh3)}2(µ-OH)2] (4). A C6D6
solution (1 mL) of trans-[Pt(Ph)(OH)(PPh3)2]27 (32 mg, 39 mmol)
was heated for 14 h at 60 °C. The solvent was removed under
reduced pressure. The resulting material was washed twice with a
1 mL portion of acetone to remove Ph3PO and dried in vacuo to
yield a mixture of anti- and syn-platinum dimers 4 in 3:1 ratio
(64%). Recrystallization from a CH2Cl2/pentane solution afforded
colorless crystals appropriate for X-ray analysis. Anal. Calcd for
C48H42O2P2Pt2: C, 52.27; H, 3.84. Found: C, 52.07; H, 3.86.
Acknowledgment. N.M. thanks the Japanese Society for
Promotion of Science for a postdoctoral fellowship for foreign
researchers (2004-2006). This work was financially supported
by a Grant-in-Aid for Scientific Research for Young Chemists
No. 17750049 and for Scientific Research on Priority Areas,
from the Ministry of Education, Culture, Sport, Science, and
Technology Japan, and by The 21st Century COE Program
“Creation of Molecular Diversity and Development of Func-
tionalities”.
1
Decomp > 175 °C. H NMR (300 MHz, CDCl3, room tempera-
ture): δ -0.46 (d, 2H, OH, JHP ) 3 Hz), 6.56 (t, 4H, PtC6H5 meta,
JHH ) 7 Hz), 6.64 (d, 2H, PtC6H5 para, JHH ) 7.2 Hz), 6.98 (d,
4H, PtC6H5 ortho, JHH ) 8.1 Hz), 7.27 (m, 18H, PC6H5 meta and
para), 7.90 (m, 12H, PC6H5 ortho). 31P{1H} NMR (122 MHz,
CDCl3, room temperature): δ 11.35 (JPtP ) 4687 Hz). IR (KBr):
νOH 3630 (vw) cm-1
.
X-ray Crystallography. Crystals of 1a, 1b, 3a, 3b, and 4
suitable for X-ray diffraction study were mounted on a glass
capillary tube. The data were collected to a maximum 2θ value of
55.0°. A total of 720 oscillation images were collected on a Rigaku
Saturn CCD area detector equipped with monochromated Mo KR
radiation (λ ) 0.71073 Å) at -160 °C. A sweep of data was done
using ω-scans from -110.0° to 70.0° in 0.5° steps, at ø ) 45.0°
Supporting Information Available: Crystallographic data for
1a, 1b, 3a, 3b, and 4 in CIF format. This material is available free
of charge via the Internet at http://pubs.acs.org.
OM060192S